Question: Solve for $y$ : $-20 = -3 + y$
Answer: Add $3$ to both sides: $ \begin{eqnarray} \\ \hphantom{-20 {+ 3}} &\hphantom{=}& \hphantom{y} \\ -20 &=& -3 + y \\ \\ {+3} && {+3} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -20 {+ 3} &=& y \\ \end{eqnarray} $ Simplify. $ y = -17$